Receiving below error sporadically in production when users are working on an assignmnet. 

.pxFlow().pyFlowParameters.HarnessType is not valid. Reason: unexpected character ')' at position 8, expected subscript (wildcards not allowed)

It happens daily for 2 or 3 times out of 1000s of transactions that users made. When this happens, users experience spinning and are stuck on the screen. 

We are on Pega Platform 8.8.1

Any insights on this exception will be helpful. TIA. 

Below is the step it fails.